One year ago this month, Mr Trump ordered dozens of cruise missiles to be fired at a Syrian air base after declaring there was no doubt Assad had “choked out the lives of helpless” civilians in an attack that used banned gases.

Inside they showed off chemicals, fuses and mortar casings they said were used by rebels to manufacture weapons.

When asked about the explosions, an Israeli spokeswoman declined to comment.

“An aggression was perpetrated on T-4 air base in several strikes that is most likely to be an American attack”, state television said in a news flash.

Rebel-held areas of the Ghouta region were hit in a major chemical attack in 2013.

Those still trapped in Douma had been nervous recently that any attempt to renege on an evacuation would only prompt Russian Federation and the Syrian aviation to resume deadly strikes.

As part of the agreement, the group’s fighters would be transported to Jarablus in northern Syria.

– ´Douma is the end´ – Six civilians were also killed and dozens more wounded as Douma rebels shelled the capital Damascus on Saturday, Syrian state media said. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world.

Over the weekend Mr Trump threatened a “big price to pay” for the suspected poison gas attack.

As images spread of children gasping and convulsing, aid groups and worldwide leaders are denouncing the Syrian regime for their alleged role in a suspected chemical attack. The Russian Foreign Ministry’s official position is that the chemical attack didn’t happen, which seems an imminently practical position given the lack of evidence, or even conceivable reason for such an attack.

The Syrian Observatory for Human Rights issued a higher death toll, saying at least 80 people were killed in Douma, including around 40 who died from suffocation.

“We have clear interests in Syria and we set red lines”, Yoav Galant of Israel’s security cabinet said after the attack. The Observatory said at least eight civilians were killed in the attacks. Other rebel groups agreed to relocate to the north after a Russia-backed government offensive in February and March that killed hundreds of people and caused catastrophic destruction.

The tweet was accompanied by gruesome images of apparent victims of the alleged attack, including women and children, with foam around their mouths. “Douma city, April 7. there is a strong smell here”, a voice can be heard saying.

Those reports could not be independently verified because of a government blockade around the town.

Last year, a joint inquiry by the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) found the Syrian government was responsible for an April 4, 2017 attack using the banned nerve agent sarin in the opposition-held town of Khan Sheikhoun, killing dozens of people. The president has often laid some blame on his predecessor, Barack Obama, for Assad’s continued grip on power after years of civil war.

On Saturday, a government source told state media that the accusations were a “farce”.

The government of President Bashar Assad has denied using poison gas.

Allegations of a government sponsored chemical attack in in Syria on Saturday comes as pro-government forces concluded an operation to liberate the region from Islamic militants that had taken control of vast swaths of the country, and only days after Trump publicly stated his intention to get USA troops out of Syria. However gaining access to samples on the ground would be hard. At the first meeting, chaired by Mr Trump’s new national security adviser John Bolton, national security heads including the secretary of defence, the acting secretary of state, the joint chiefs of staff and Syria desk directors will assess the findings and options available to Washington.